A cash machine at Sydney's Luna Park was reportedly dispensing $50 notes instead of $20 last week after it was loaded incorrectly by park staff.

Up to 20 Luna Park workers accused of taking advantage of the faulty iCash machine in the Big Top pavilion were sacked and escorted from the park on Friday, according to the Sydney Morning Herald. News of the malfunctioning machine spread quickly among park staff, with some reportedly returning to the ATM many times to drain their bank accounts.

iCash chief executive Kim Stewart said $50 notes had been placed in where the $20 were supposed to be, and vice versa by the harbourside park's staff.

The amusement park management caught the staff out and asked them to sign documents saying that they would repay the money, but the police were not brought in.

Luna Park managing director Peter Hearne would not comment on the alleged fraud.

"It's a confidential matter between the company and the staff," he said.